After the attack on Pearl Harbor during WW2, Canada acted to declare war on Japan before the U.S. did.
Officially, Canada declared war on December 8th, 1941—the same day the U.S. and Great Britain declared. However, MacKenzie King and the Canadian Cabinet decided to declare war on the 7th. So, Canada acted first.
Four hours after Pearl Harbor (in equivalent time), Japan had attacked Hong Kong. “Canada had its own reasons to declare war,” writes John Ferguson. “The Hong Kong garrison of 14,000 included 2000 Canadians. The colony surrendered on Christmas Day after a horrible, bloody battle that included hand-to-hand fighting. There were 10,000 casualties, including 6000 Japanese. The Japanese had an overwhelming force of 52,000. so in the end they won a battle of attrition. The Canadians took 700 casualties, including 300 killed. Many more died later in Japanese prison camps.”